简单密码，c++实现

#include <iostream>
#include <string>
#include <map>

using namespace std;

int main()
{
    string code;
    string out;
    map<string, char> littleMap{ {"abc",'2'},
                                {"def",'3'},
                                {"ghi",'4'},
                                {"jkl",'5'},
                                {"mno",'6'},
                                {"pqrs",'7'},
                                {"tuv",'8'},
                                {"wxyz",'9'}
    };
    cin >> code;
    for (auto& i : code) {
        if (isupper(i)) {
            if (i == 'Z') {
                out.push_back('a');
            }
            else {
                out.push_back(tolower(i) + 1);
            }
        }
        else if (islower(i))
        {
            for (auto &mp: littleMap)
            {
                if (mp.first.find(i) != mp.first.npos) {
                    out.push_back(mp.second);
                    break;
                }
            }
        }
        else
        {
            out.push_back(i);
        }
    }
    cout << out << endl;
}